1. Field of the Invention
The invention relates in general to transformers and in particular to transformers having winding units.
2. Description of the Related Art
Transformers are widely applied in electronic devices to transform drive voltage from circuits, such as conventional power transformers to lower voltage or step-up transformers used in monitors to raise an operating voltage from circuits. Conventional transformers can be made to measure for various types, wherein miniaturization is usually a significant requirements.
Generally, a transformer requires at least a primary winding and a secondary winding. The primary winding receives an input voltage, and the secondary winding generates an output voltage by electromagnetic induction from the primary winding. Function of the transformer depends on turn ratio of the primary and secondary windings.
Referring to FIG. 1, a conventional transformer 10 primarily comprises a ferromagnetic core 11 and a bobbin 12. A primary winding 13, an insulating tape 14 and a secondary winding 15 are sequentially wound around the bobbin 12. As shown in FIG. 1, the insulating tape 14 is wound at the exterior of the primary winding 13, adversely increasing dimension of the transformer and complicating assembly. Moreover, when windings are not appropriately arranged, the transformer can fail and influence yield. Further, the insulating tapes may obstruct heat dissipation, shortening life of the transformer and adversely affecting peripheral electronic devices.
In this regard, it is important to provide a transformer having low cost, simple structure, small dimension and high heat dissipation efficiency.